We propose several interrelated experiments on a system especially well suited to study the development of the nervous system and of behavior - the escape system of the first instar nymphs of the cockroach Periplaneta americana. Our major objectives are to determine: (1) whether there are age-dependent differences in the strength of synaptic connections among identified neurons, and whether there are neuroanatomical correlates of these; (2) what information contained in two sensory neurons is used to compare the strength of excitation of these two neurons in obtaining information about the location of a sensory stimulus; (3) what changes occur in the wiring of a neuronal circuit as a sensory system grows from a minimal system of only 4, to as many as 440 sensory neurons; (4) how are sensory systems "calibrated" by experience to correct for potential errors of encoding resulting from imperfections during development.